MapBox.com and our toolset will no longer officially support Windows Internet Explorer 7. We’ll continue to support Internet Explorer 8 and 9, and we’ll test against Internet Explorer 10 and support it upon release in August. So while much of MapBox’s code will continue to function correctly in Internet Explorer 7 - there will be no browser detection or forced degradation - some features will only work well in modern browsers.

This effects very few people. Late last year, Microsoft started to automatically upgrade IE7 to IE8 in order to stem the tide of malware caused by the six-year-old browser. Meanwhile, the market share of Internet Explorer 7 has dropped to 1.53% and has been eclipsed by new browsers like Mobile Safari, the default on iPhone and iPad.

Throughout the development of MapBox Hosting, TileMill, and our broad APIs, we’ve made great efforts to maintain compatibility with as many devices and browsers as possible. This includes developments like our UTFGrid specification, which makes it possible to interact with maps in browsers that don’t correctly support any vector standard.

But there are many important things that IE7 doesn’t support. JSON, the data format we support in our API and a widely accepted standard, isn’t supported natively. The technologies behind exciting new client-side mapping possibilities like Canvas and SVG are completely unsupported by the browser. IE7’s support for CSS is also extremely lacking, as well as a lack of support for the hashchange event, which gives us the ability to link to specific areas of sites and maps. The lack of support for data uris - content embedded within a local string - means that maps can’t take advantage of caching and our CSS can’t use inline images, which improve performance in mapbox.js.

Internet Explorer 8 is still a gradual improvement in terms of features compared to modern browsers but fixes many bugs that previously required ‘hacks’, or complex workarounds in IE7. IE8 also supports a significantly wider, though still incomplete, range of web standards.

Supporting Internet Explorer 7 has been a costly endeavor, but more importantly, continuing to do so would limit the kind of innovation MapBox can produce, especially on mobile. By continuing to support IE8, any users with Windows XP and newer who haven’t disabled auto-updates will still be able to use our tools.